Classes were a little smaller than usual at Dixon High School on Monday morning. Forty-one students were missing.

"We think that's a combination of all the sickness going around and some of our students may have wanted to start spring break just a little bit early," said Superintendent Dawna Burrow.

Seventeen students have been diagnosed with mono since last Wednesday. It started with a couple of baseball players who may have shared water bottles, and the diagnosis spread quickly.

"By probably 1 in the afternoon, I heard we had a possibility of six cases," Burrow said.

The high school immediately started taking extra precautions. It turned off the water fountains, substituting with large water jugs and disposable cups.

"When I talked to the nurse practitioner, she told me one of the prime ways, if they weren't just picking up a glass or a bottle and drinking after each other, one of the prime ways is students will often put their mouth down on the water fountain when they get a drink," said Burrow.

Staff at Dixon High School are also taking other steps to prevent the mono from spreading. They're doing extra sanitizing in the kitchen and throughout the school on a daily basis. They hope those steps will stop the spread of the mono and the other bugs going around, like colds and flu, especially with standardized testing only a few weeks away.

Nine of the students diagnosed have already returned to class, after getting medical clearance.

Mono is spread by a virus that's found in the saliva and mucus. Symptoms can include fatique, fever, sore throat, body aches and it can last for up to a couple months. Athletes who've been diagnosed won't be able to go back to their sports for a while because of the risk of a ruptured spleen.